Recently finished up a project for a customer.
Mauser square bridge style rear bases with inserts.
Machined from solid 4140 hand polished ready to blue.
Would not have been able to make these very easily if it were not for getting the CNC upgrade on my mill. That saved days of work

Tell me what you think.

Base and insert assembled



Base and insert




Base and insert



Insert only





Insert only


Base is .700 across the top by 1.250 long 3/8" dove tail
Insert is .386 high over all with a .180 aperture .700 long .250" wide across the exposed area.

Nice work. What CNC package did you add to your mill and any pictures of the set ups?

I bought an old Acurite Mill power. It was used and a good price @ $2000. It's only two axis and it's on an old bridgeport but it will make me some money till I can swing a newer VMC

I'll post some picks of the fixtures.

Thats a good price for the mill. Again nice work.

Ok here are the pics of the process


Set blocks up to cut concave surface


After blocks are cut


Make fixture to locate on concave surface. Everything will be referenced off of this surface since this is the surface that will locate on the receiver.


Fixture in above pic with stop on side just insert block clamp in place make you cut on one side only for the scalloped edge. flip block over in fixture and repeat the cut.



Customer emails and says "Opps I made a mistake and need the blocks cut smaller". At least he didn't ask me to make them bigger



Cut the dove tail, Drill and counterbore holes again using same fixture above so everything is on the same reference surfaces


Fixture for inserts. Just flip this up 90 degrees and cut the top surface of the insert and drill aperture holes



Mill with CNC control Well not yet as you can see in the pics I was installing the timing belts and drilling holes in the timing gears.
Took a couple of days to install everything but she work perfect now just not as rigid as I would have hoped for but it is a manual conversion so what do you expect.
A newer VMC will be coming in the near future

quote:

Originally posted by J_Zola:
Thats a good price for the mill. Again nice work.

Thanks for the complement. That price was JUST the CNC control
The mill was a trade for labor years ago Still a good deal though considering a new bridgeport with a prototrak is like $25K. A HAAS tool room mill is not much more then that and a much better machine then a converted manual machine
It gets the job done for now though.

Thanks for the pictures of the fixtures and the steps. The true story on how a part is made is in the fixtures. You still got a good deal on the CNC package. HAAS has really killed the Bridgeport market. Setting my shop up this spring and going to turn and burn until I own a HAAS.

Is that a compound curve on the bottom of the base or single radius?

That is a mirror image of the 98 mauser rear bridge profile. It's a radius in the center that fades into an angle on each side. I set one of these on my 98 and even with the excessive polishing of my action. (lower grade action sold through a large sporting goods chain) it fit perfectly. This was reproduced from a casting the customer took with accraglass. Sent me the models And I duplicated them I also recorded the dimensions for future use



Set on my 91 just for looks but you can see the complex shape of the concave surface.



Little better shot of the base

The outside scallop is a 1"radius

Very good KC! I wouldn't expect any less from you.
Butch

Hey thanks Butch. but wait till you see the set for my rifle .
I'm going to put double square bridges on my 91 arg Mauser. Those should be very nice. Dove tailed for Tally rings as well

Looks nice KC, I like it.

Nice work. Those are nicely made.

That said, let me ask a question. Why has there always been so much interest in the whole square bridge thing? I know that custom gunmakers must like them, because quite frankly, they are expensive. They are different, but other than that, why? If an action is not a true integral square bridge, then they are still just a screwed on scope mount. You can silver solder them on, but you can do the same to a set of Talleys. They are quite a bit heavier than regular mounts, and often put the scope higher, which is the last thing abig game rifle generally needs. In my opinion, the extra weight is a big detriment on a heavy rifle. The extra inertia puts more load on the screws. So, why a heavy square bridge milled for Talley rings vs a light Talley?

i'm not trying to flame. I honestly have never understood this, and actually have never really liked the looks of the square bridge, but understood its advantage when it was really part of the action. Ruger does the same thing for the same reason with all it's bolt actions.

For one a Ruger is not a square bridge In the traditional sense of the meaning. It's a bastardized proprietary mount thats ugly as sin. Functionally yes it's a square bridge.

other then that I just like the look as it looks like the receiver and base was machined as one unit not a bolt on base. A lot of the bolt on bases just look like crap. Weaver ring a bell?? Perfectly functional, does a great job. But again Ugly as sin. Even tally bases leave a little to be desired.

As for the weight thing It doesn't bother me and on big game calibers you should mount it accordingly i.e. 8-40 screws. Yes a heavier mount will put more stress on the screws but On my 91 thats a .220 swift I don't think recoil is going to be and issue. Now a magnum yes then we would have an issue and again should be mounted accordingly

For me It all comes down to looks Nothing else.

quote:

Originally posted by Art S.:
That said, let me ask a question. Why has there always been so much interest in the whole square bridge thing?

Art S

Fair questions. Since I am the customer who commissioned these from Kerry I'll take a stab at answering them. (Just to be clear, I went to Kerry with an idea and through his skill with computer modeling and machining he made happen. Originally I wanted a length of steel shaped into "square bridge" form that could be cut up for use as square bridges and peep sight bases. Because Kerry was so adept at generating computer models then reproducing them in steel while giving great advice along the way, before I knew it he had designed the entire sight. In other words, I had an idea but his skill and patience made it happen.)

So, from an aesthetic point of view, why square bases? Most importantly Mausers have a rear bridge that is much lower than the front ring(+-.160"). This means that the rear base will be pretty tall no matter the type. Couple this with the fact that the bases are usually the flat sided while everything one the action(and rifle) are more flowing and rounded, the rear base tends to stick out like a sore thumb. Many custom makers like to leave the charger hump intact because it lessen the visual impact of the rear base.

To my mind the concave sides of the square bridge accomplishes the same effect.

I did not want to have a "faux square bridge" but rather a simple base that is inspired by the lines of the original Mauser square bridge. In fact I decided on a 1" radius concave which is gentler than the original because, to my eye, the original concave is too radical.

As to the weight: the top of my base is .700" which is the same as most Redfield/Leupold bases. So the only extra weight is picked-up in the "wings" that flare out wider than the top of the base. If you look at the picture below and draw a line from the outer edge of the top of the base straight down you will see that there is really not too much extra steel there compared to a standard rectangular base.




According to my scale the Leupold rear base is 1.25oz and the custom base is 1.75oz. Further weight could be saved by milling a duck-pong on the underside of this base. I will most likely do that to the two bases that I will uses for rear scope mounts(for JC Higgins rifles with the odd rear hole spacing).

For the other bases that are dovetailed and include the peep sight insert, I don't think 1.75oz total is too much to worry about. A couple of these are destined for bigbores and they may get a third 6x48 mounting screw(or 8x40) or I may have them soldered on. Regardless, with a total weight of 1.75oz and a very low center of gravity, I can't imagine them over stressing the screws. Especially when you consider that few scope and mount combos come in under 16oz total.(BTW I hate heavy scopes which is why all my rifles have leupold 2.5x(6.5oz) and 4x(9.3oz) fixed power scopes.)

As far as putting the scope higher: that is only a problem if they are poorly designed. These peep sight bases are only .340 high, which is lower that any Mauser rear mount AFAIK. The bases that I will use as rear scope mounts are .430 which is the standard height for Buehler bases.

Why not use the Talley? Talleys are the best standard off the shelf mounts available. They are also too high and too ugly IMO. Their rings look great, but are too high. Their bases are just plain ugly...

Calling Ruger's receiver treatment "square bridges" is like referring to Rosie O'Donnel a single woman.

quote:

Originally posted by JBrown:

Calling Ruger's receiver treatment "square bridges" is like referring to Rosie O'Donnel a single woman.

That's what I was getting at. Great analogy

The other thing is. If looks didn't matter we'd all have Picatiny rails and bulky ass tactical rings that look like shit.

Would you consider selling these as. A set?

quote:

Originally posted by aDakota7:
Would you consider selling these as. A set?

I'm not sure if you are asking me or Kerry, but I am not looking to sell any of mine.

Kerry is willing to make more, I believe. But I'll let him answer that.

No matter how you cut it there is no peep sight on the market that comes close to the quality of this one. It looks great and is indestructible.

Well Jason decided he's going to hang on to the ones he's got. PM me for details on what you'd like. The bases can be made longer or shorter. slightly taller or slightly shorter and the inserts are fully customizable, Meaning you give me the aperture diameter you want, the hight above bore centerline, and I do the rest. I can also make some calculations but your front sight will need to be insertable or adjustable to be dialed in. I can also make an express style sight insert that can be machined (filed) to adjust your POA. Just like traditional express sights. All that at a flat fee.

That is one sweet setup!

Jason, please post some pics when you get them on a rifle!

Best,
Dave